Heating Up, Filling Up
by sarrenwakk
Summary: Karkat is busy doing some sort of "science work" in the ecto lab, when his matesprit Terezi stops by. When she reads a label on an experiment of some sort telling her to specifically not do anything with it, she shrugs it off and drinks it. Karkat is furious, but in the end turns out happy, because of the contents of the vial Terezi drank. (Contains an inflation story and science)


Karkat sighed as he slapped his forehead with his arm, a loud cackle echoing down from the hall. Terezi was on her way to disturb him again, and right now, he was busy working in the damned ectobiology lab. Terezi popped into the room, leaning over Karkat, who was busy mixing together some chemicals, writing some stuff down on a clipboard. Terezi licked up his cheek and he reeled back, moving his face away from her.

"FUCK OFF TEREZI, I'M BUSY DOING SOMETHING IMPORTANT RIGHT NOW."

"4WW, K4RKL3S, WH4T'S MOR3 1MPORT4NT TH4N M3, YOUR B34UT1FUL M4T3SPR1T?"

Karkat sighed and sat back up in his seat, leaning over to give Terezi a quick kiss on the cheek before returning to his work. Terezi let out a displeased grunt as she went around the room, looking over vials and tubes, listening to pops and bubbles around her. She kept wandering until a strange red vial labeled "DO NOT TOUCH, DO NOT GLANCE AT, DO NOT EVEN MENTION" caught her eyes. She drifted over and giggled quietly, picking up the vial.

"K4RKL3S, WH4T'S 1N TH1S V14L, WH1CH 1S STRONGLY L4B3L3D H3R3?"

Karkat tensed up at the mention of a vial, spinning around in his chair, his eyes wide.

"TEREZI, PUT THAT THING DOWN! IT'S DANGEROUS TO ANY LIVING CREATURE!"

Terezi raised an eyebrow and cackled, removing the cap on the vial, a sweet red flavor drifting out.

"TEREZI DON'T EVEN THINK ABOUT IT. THAT THING IS DEADLY POISON. IT WILL KILL YOU."

Terezi shrugged and titled her head back, tipping the vials red liquid into her mouth. She promptly swallowed and felt a rush of cold as the liquid settled in the pit of her stomach.

"OH PL34S3, 1'V3 1NG3ST3D PO1SON B3FOR3. 1T'S NO B1G D34L. B3S1D3S, 1 W4S HUNGRY, K4RKL3S."

Karkat grumbled and slapped his forehead as he walked over to her and groaned, looking at the vial.

"OH, WAIT, THIS ISN'T THE POISON. THE POISON WAS IN A GREEN VIAL. THIS IS…"

"1S WH4T, K4RKL3S?"

Karkat blushed as red as the contents of the vial, shaking his head a bit.

"TEREZI, THIS IS A HYPER CONDENSED DOSAGE OF A DANGEROUS GASEOUS SUBSTANCE. IT WILL SLOWLY WARM UP AND EXPAND, FILLING ANY CONTAINER IT OCCUPIES. THE ONLY REASON IT DIDN'T REACT ALREADY IS BECAUSE THIS VIAL IS MADE OF A VERY UNREACTIVE METAL AND GLASS COMBINATION. TEREZI, YOU JUST DRANK A VIAL OF SOMETHING I WAS STILL STUDYING!" Karkat groaned as he pinched the bridge of his nose.

Terezi cackled and shrugged.

"W3LL, NOW YOU C4N STUDY 1T UP CLOS3 4ND P3RSON4L," she said, kissing Karkat lightly before hugging him.

Karkat sighed and hugged her back, but let go after a few seconds.

"TEREZI, THE EXPANSION WILL START SOON. SINCE THE DOSAGE WAS KIND OF LOW, I DOUBT YOU WILL EXPAND TOO MUCH, SO YOU CAN KEEP YOUR CLOTHES ON, IF YOU PREFER IT."

"OH, 1'D PR3F3R TO T4K3 TH3M OFF, BUT 1F 1 D1D, NO STUDY1NG WOULD G3T DON3, NOW, WOULD 1T?"

Karkat blushed again, nodding solemnly and shaking his head, grabbing his clipboard and flipping to a new page. Terezi stood there and sighed, letting out a small hiccup. Karkat raised an eyebrow as Terezi hiccupped again, a suden look of discomfort falling on her face. Karkat began to jot down notes as Terezi continued to hiccup, unaware of her belly slowly filling up like a balloon, her skin becoming taught as she filled with the gas. Karkat looked up again, and remarked on her belly, which Terezi was now aware of. She grunted as she felt her once loose shirt tighten around her stomach, gurgles and pops echoing out of her body. Karkat blushed deeply and jotted down some more notes, occasionally glancing back up on Terezi to see if anything else had changed.

Terezi moaned softly and pulled her shirt off, gasping softly as she rubbed her now bulbous and swelling tummy with her hands soothingly, and her expansion seeming to come to an end. Terezi's belly shook as her navel popped out, signaling she was full, and there was nowhere for the gas to escape to. Terezi hiccupped one last time and cooed softly, her hands exploring her now full belly. Karkat stood up and sighed, clicking his pen and setting down his clipboard. His face was a bright red as he walked over to Terezi, whose face was now also flushing teal.

"SO, D1D YOU G3T 3NOUGH NOT3S?"

"YES, I'M SURE 1 DID. BUT NOW, I WANT TO STUDY THE EFFECTS UP CLOSE, IF YOU DON'T MIND."

Terezi's face flushed ever more as she nodded her head and felt Karkat's hands knead her blimp of a stomach, feeling a pressure build as he pushed in on her belly. She moaned out softly as she felt his hands feel around her body, caressing every part of her taught and yet squishy tummy. Karkat pulled back and sighed, leaning over to kiss her lightly. Terezi gasped and shut her eyes, twisting her body a bit away to make sure her stomach would not prohibit the kiss. Karkat grunted and pulled away, a hint of a smile on his lips.

"SO. I BELIEVE YOU OWE ME THAT GAS BACK," he said as he heard a gurgle from her stomach. His eyebrows raised and he chuckled.

"OR MAYBE NOT," Karkat said as he returned to his chair, Terezi now confused. She heard another low gurgle, and then a fizzle as she hiccupped again.

"K4RKL3S! *H1C* WH4T'S H4PP3N1NG?!" Terezi asked, her voice raising. She looked down and gasped, feeling around, realizing her breasts were expanding slowly, her bra straps digging into her flesh. Terezi moaned and reached behind her, unclasping her bra and throwing it to the side.

"WELL, I TOLD YOU. THE GAS EXPANDS UNTIL THE CONTAINER IS FULL. EVIDENTLY, BY YOUR CURRENT SITUATION, I WOULD GUESS YOU'RE NOT FULL."

Karkat clicked his pen again and began jotting down more notes as Terezi's body continued to expand, her breasts now almost as big as her head. She moaned loudly and panted, feeling the gas tease her body's skin, stretching it out until she was full, but still firm, still elastic. Terezi bit her lip as her hands explored her growing form, feeling around her sensitive breasts and round, full, tummy. She sighed and hiccupped again, her breasts stopping their expansion.

Karkat looked up and blushed fiercely, looking over her curvy form. Before, she had been curvy, but she had always worn looser clothes, ones that didn't accent her curves. Karkat looked away and back down to his notes, making sure she didn't see his gaze, or smell his blush.

However, Terezi was too busy with her own problems to worry about his red blush, or his gaze. Her whole form seemed to wobble softly with every breath she took, and she felt a little heavy, most of her weight now located towards her bottom, since the gas was keeping her all buoyant. Terezi sighed, and was surprised to hear another hiccup. Where could the gas go this time? It had already filled her breasts, her belly, her-

Oh.

Terezi blushed a deep teal as she felt the seat of her pants tighten on her ass, and the front of her pants tighten on her inner thigh and crotch. She gasped as she reached around her blimped belly and unbuttoned her pants, just as she felt everything down there puff out again. Terezi gasped and pulled off her pants, exposing her (once loose) boxers to Karkat. Karkat looked up at the exact moment she took off her pants and blinked, looking at the scalemate prints on her boxers. They appeared quite cute to Karkat, and he would have expressed how cute they were, if not for the fact that his current situation was calling for studying, not admiration. Karkat shook his head and began taking notes, Terezi's pants and moans coming out in little gasps as her booty continued to expand.

Terezi hiccupped one last time as her expansion stopped her body as full as it ever could be. She groaned and tried to move, but realized that was more difficult than it used to be. Karkat grinned and put down the clipboard again, moving close to her. Terezi's body was quivering softly, Terezi slowly moving towards Karkat, her body bouncing with every step she took. Karkat giggle softly as he looked at his waddling matesprit, who was blushing and grumbling, trying not to fall, having a very hard time moving around with her new and bloated form.

Karkat smiled and kissed her softly as his hands rubbed down her frame, making sure she felt pleasure instead of pain. Terezi blushed and leaned into the kiss, sighing softly, and leaning into the kiss as much as she could. The two of them kissed for a few seconds until Terezi broke off and cackled, licking up his blushing red cheek.

"SO, TEREZI, WHAT DID WE LEARN TODAY?"

"1F TH3R3 1S 4 STRONGLY WORD3D L4B3L, DR1NK FROM TH3 CONT41N3R FOR SC13NC3."

Karkat rolled his eyes and grumbled, running his hands through Terezi's hair.

"YOU KNOW, WE STILL HAVE TO GET THAT GAS OUT OF YOU, AND CONDENSE IT BACK."

Terezi blinked and tilted her head.

"HOW 4R3 W3 GO1NG TO M4N4G3 TH4T?"

Karkat looked around and found an empty air tank, pulling off the hose and handing it to her.

"THE PRESSURE DIFFERENCE FROM YOU TO THE TANK WILL CAUSE THE GAS TO LEAK OUT OF YOU AND INTO THE TANK. I WILL HAVE TO PUT IT ON THE HIGHEST SPEED THOUGH, TO MAKE SURE THE GAS CANNOT EXPAND FAST ENOUGH TO TRY AND FILL YOU BACK UP, SO, ONCE YOU ARE EMPTY YOU MAY FEEL A LITTLE BIT LIGHTHEADED, BUT I WANT TO MAKE SURE ALL THE GAS IS BACK IN HERE, OKAY?"

Terezi nodded as she put the hose in her mouth, clamping her lips firmly around the nozzle. Karkat spun the dial up to the fasted speed and Terezi breathed out the gas into the hose, making her body deflate even quicker than it had inflated. Within a few seconds, only her belly was inflated, and that passed a few seconds later as her stomach flattened back out to its usual form, her belly protruding only a few inches over her boxers, Terezi wobbled softly as the last of the gas left her and entered the tank, Karkat switching off the tank's pressure, Terezi removing the hose from her mouth. Terezi breathed in deeply, the air flooding her lungs and making her still naked chest rise a bit in the air. Karkat moved the tank off to a condensing unit nearby and left it there to be worked on later. He turned back to Terezi and grunted, suddenly aware of her naked form in front of him. Terezi blinked and bit her lip, swaying her hips a bit in front of him. Karkat blushed and looked away, moving back to his science work.

"TEREZI, ARE YOU BUSY LATER? I WANTED TO SEE IF YOU COULD, UH, HELP WITH SOME FUCKING PROJECTS. A-AS IN…"

Terezi cackled and moved over to him, leaning beside him, Karkat's gaze suddenly on her bouncing orbs.

"WHY DON'T 1 H3LP YOU R1GHT NOW?" Terezi said as she spun Karkat's chair around and sat forcibly in his lap, kissing him deeply on the lips, her tongue darting into his mouth and licking everything inside. Karkat groaned and shut his eyes, giving in to the happiness and peaceful nature of the moment, their mouths and tongues dancing for the next few hours.


End file.
